From c374bfd9fdff02a0cff85d005488967b1b0f675e Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Fri, 12 Feb 2021 21:08:46 -0300
Subject: [PATCH] Add Phi support

---
 include/sirit/sirit.h     | 6 ++++++
 src/instructions/flow.cpp | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/include/sirit/sirit.h b/include/sirit/sirit.h
index 781f84a..0a204d7 100644
--- a/include/sirit/sirit.h
+++ b/include/sirit/sirit.h
@@ -232,6 +232,12 @@ public:
 
     // Flow
 
+    /**
+     * The SSA phi function.
+     * @param operands An immutable span of variable, parent block pairs
+     */
+    Id OpPhi(Id result_type, std::span<const Id> operands);
+
     /// Declare a structured loop.
     Id OpLoopMerge(Id merge_block, Id continue_target, spv::LoopControlMask loop_control,
                    std::span<const Id> literals = {});
diff --git a/src/instructions/flow.cpp b/src/instructions/flow.cpp
index e40800c..85700d2 100644
--- a/src/instructions/flow.cpp
+++ b/src/instructions/flow.cpp
@@ -12,6 +12,12 @@
 
 namespace Sirit {
 
+Id Module::OpPhi(Id result_type, std::span<const Id> operands) {
+    assert(operands.size() % 2 == 0);
+    code->Reserve(3 + operands.size());
+    return *code << OpId{spv::Op::OpPhi, result_type} << operands << EndOp{};
+}
+
 Id Module::OpLoopMerge(Id merge_block, Id continue_target, spv::LoopControlMask loop_control,
                        std::span<const Id> literals) {
     code->Reserve(4 + literals.size());